BMW Z3 Radiator Fan Failure Causing Overheating Issues

Hi there! I had a similar issue with my BMW Z4 (2002) last summer. I have some experience working on cars, mostly basic maintenance and minor repairs. The symptoms you're describing remind me exactly of what I went through. Initially thought it was the fan too, but it turned out to be a faulty speed sensor that wasn't sending the correct signals to activate the cooling system. Had it checked at my regular workshop and they diagnosed it pretty quickly. The repair cost me about 250 Euro, including parts and labor. Before you spend money on a new fan, could you share: Does the fan work at all when you first start the car? What's your coolant level like? Have you scanned the check engine code? For reference, I also own a BMW 3 Series, and these cooling system issues are somewhat common in these models from that era. Let me know these details and I might be able to help further!

Thanks for reaching out! Just got back from checking my car again. My Z3 is at 187623 KM and had its last service about 3 months ago. When I checked earlier, I noticed the fan doesn't spin at all at startup. I just topped up the coolant last week, so that's good. Haven't scanned the code yet, but heading to my 's place tomorrow, he's got a scanner we can use. You make a good point about the speed sensor. That's definitely cheaper than replacing the whole fan assembly. Think I'll check the sensor and wiring first before buying any parts. These old Bimmers can be tricky with their cooling systems, but they're worth the hassle! I'll update once I get those codes read. Really appreciate the help!

Hey again! Good to hear back from you about your Z3. You know, after I fixed my Z4's speed sensor issue that I mentioned before, I actually ran into another similar overheating problem about six months later. The symptoms were exactly like what you're describing, no fan at startup, even with good coolant levels. Here's what's interesting: in my second round with cooling issues, it actually WAS the fan assembly that failed. I initially didn't want to believe it since I had just dealt with the sensor thing, but the diagnostic codes confirmed it. Cost me around 400 bucks for the whole fan assembly, but at least the installation wasn't too bad. Since you're getting the codes checked tomorrow, look out for P0485 if it shows up, that's the one I got with my fan failure. But definitely check those wire connections too. I remember finding some corroded connectors while fixing mine. Just a heads up, might want to clean those connections anyway, even if they're not the main problem. Quick tip from my experience: if you end up needing to replace the fan, make sure to check the fan shroud for cracks while you're in there. Mine had a hairline crack that I almost missed, and it would have caused problems later. Let me know what those codes say when you get them. Always happy to help out another BMW owner!

Thanks so much for the detailed follow-up! That's super helpful info about your experience with both the sensor and fan issues. I actually just got back from my 's place, and we pulled the codes. Wouldn't you know it, got that exact P0485 code you mentioned! We also checked those wire connections like you suggested, and found some pretty crusty-looking ones near the fan assembly. Cleaned them up, but the fan still won't kick in. After everything you've shared, I'm pretty convinced I'm looking at a fan replacement too. Really glad you mentioned checking the shroud, that's definitely going on my inspection list. Think I'll bite the bullet and order the fan assembly this week. The car's been good to me, so I guess it's time to return the favor! Really appreciate you taking the time to share your experiences. It's always better going into these repairs knowing what to expect!